Gasification is widely used throughout the energy and chemical industries. Gasifiers come in an extremely wide range of sizes and configurations ranging from handheld to 30 stories tall. Gasification of biomass is an important and established technology to provide combustible gases which feed other processes such as electricity production. During World War II, it is estimated that about 1 million small downdraft gasifiers were pressed into service to power engines while gasoline was extremely hard to obtain.
Biomass gasification is typically performed with air, leaving a large residual of nitrogen gas in the resultant combustible gas stream. The ideal conversion of biomass carbon to synthesis gas with air can yield nearly 40% carbon monoxide in nitrogen, but virtually no hydrogen at all if there is no input water and no partially charred input feed. In practice, there are hydrogen sources in the input feeds, but nitrogen and carbon monoxide dominate the output with further degradation via contaminants, irregularities in flow and control which result in high concentrations of carbon dioxide and water vapor in the output gas further degrading the hydrogen concentration.